Clive Rosfield deals damage equal to that spell's mana value to that player or a planeswalker that player controls
Usually Ive seen this card in the 99 of Endrek Sahr, Master Breeder
However, we can trace its approximate origins back to this card: To my knowledge, Core Set 2015 's Goblin KaboomistGoblin Kaboomist is the first card to create expendable, noncreature artifact tokens with a minimal effect on the game (this is the part where commenters slay me with an obscure card from Homelands )
An Introduction to Premodern Ben introduces us to Premodern: A 1v1, 60-card format spanning from Fourth Edition through Scourge that recreates 1995 - 2003 Magic without Power Nine or original Duals
Your opponents will often shift aggro to whoever is in control of the Crown, rather than whoever brought the Crown to the table
Should we change the mechanic's name